Multi-branch well completion system and method

Abstract

The multi-branch well completion system comprises an upper well completion pipe string, a middle well completion pipe string, a lower well completion pipe string, a first branch well completion pipe string and a second branch well completion pipe string, wherein the upper well completion pipe string, the middle well completion pipe string and the lower well completion pipe string are sequentially arranged in a main well hole from top to bottom; the first branch well completion pipe string is arranged in a first branch well hole; the middle transverse deflection device is communicated with the main well hole and the first branch well hole, one end of the middle multi-direction connecting device is coupled with a first tie-back device of the first branch well completion pipe string, and the other end of the middle multi-direction connecting device extends to the main well hole and is upwards connected with a first middle packing device located above the first branch well hole; the lower transverse deflection device is communicated with the main well hole and the second branch well hole, one end of the lower multi-direction connecting device is coupled with a second tie-back device of the second branch well completion pipe string, and the other end of the lower multi-direction connecting device extends to the main well hole and is upwards connected with the first lower packing device located above the second branch well hole. According to the invention, the damage risk of each component when the branch completion pipe string is deployed into the branch borehole is reduced.

Description

Technical Field

[0001] The invention relates to a multi-branch well completion system and method. Background Art

[0002] In many well applications, a main wellbore is drilled in the underground formation, and multiple lateral branch wellbores are drilled to extend from the main wellbore to the lateral branch wellbores to improve the oil and gas recovery rate of the well. The required completion string is run into the main wellbore and the lateral branch wellbore, and the production liquid flow of the lateral branch wellbore and the main wellbore is independently monitored and controlled. Summary of the invention

[0003] In order to enrich the types of multi-branch well completion systems and reduce the risk of damage to various components in the multi-branch well completion system, the present invention proposes a multi-branch well completion system and method. The technical solution proposed by the present invention is as follows:

[0004] In a first aspect, the present invention provides a multi-branch well completion system, comprising: an upper completion pipe string, a middle completion pipe string and a lower completion pipe string sequentially deployed in a main wellbore from top to bottom, a first branch completion pipe string deployed in a first branch wellbore and a second branch completion pipe string deployed in a second branch wellbore;

[0005] The middle completion pipe string includes a first middle isolation device, a middle multi-directional connection device, a middle lateral deflection device, a first middle coupling device and a second middle coupling device;

[0006] The lower completion string includes a first lower isolation device, a lower multi-directional connection device and a lower lateral deflection device;

[0007] The middle lateral deflection device is connected to the main wellbore and the first branch wellbore, and is used to deploy the first branch completion string into the first branch wellbore;

[0008] One end of the middle multi-directional connection device is coupled to the first tie-back device of the first branch completion string, and the other end extends to the main wellbore and is upwardly connected to the first middle isolation device located above the first branch wellbore;

[0009] The lower lateral deflection device is connected to the main wellbore and the second branch wellbore, and is used to deploy the second branch completion string into the second branch wellbore;

[0010] One end of the lower multi-directional connection device is coupled to the second tie-back device of the second branch completion string, and the other end extends to the main wellbore and is upwardly connected to the first lower isolation device located above the second branch wellbore.

[0011] In some embodiments, the upper completion string includes an upper coupling device;

[0012] The middle completion pipe string includes a first middle coupling device and a second middle coupling device;

[0013] The lower completion string includes a first lower isolation device;

[0014] The upper coupling device is connected to the first middle coupling device;

[0015] The second middle coupling device is connected to the first lower isolation device.

[0016] In some embodiments, the lower completion string further comprises: a second lower isolation device, a filtration device, a third lower isolation device and a lower sand control screen assembly connected in sequence from top to bottom by the oil pipe;

[0017] The first lower isolation device is located above the second branch wellbore, and the second lower isolation device is located below the second branch wellbore.

[0018] In some embodiments, the second branch completion string includes a second branch isolation device and a second branch sand control screen assembly connected by a tubing;

[0019] The second tie-back device is coupled to one end of the lower multi-directional connection device;

[0020] The other end of the lower multi-directional connection device extends to the main wellbore and is connected to the first lower isolation device.

[0021] In some embodiments, the middle completion string includes a second middle isolation device, a first middle flow control device, a middle downhole monitoring device, and a second middle flow control device connected by a tubing;

[0022] The first middle isolation device is mounted on the middle lateral deflection device, and the middle lateral deflection device is connected to the second middle isolation device;

[0023] The first middle isolation device is located above the first branch wellbore, and the second middle isolation device is located below the first branch wellbore;

[0024] The first middle flow control device is used to control the flow of fluid flowing from the main wellbore through the middle completion string;

[0025] The second middle flow control device is used to control the flow of fluid flowing from the second branch wellbore through the middle completion string;

[0026] The middle downhole monitoring device is used to obtain various sensor data of downhole measurements.

[0027] In some embodiments, the first branch completion string further includes a first branch isolation device and a first branch sand control screen assembly connected by oil pipes.

[0028] In some embodiments, the upper completion string includes an upper isolation device, an upper flow control device, an upper downhole monitoring device, and a locking device connected by a tubing;

[0029] The upper isolation device is located above the upper flow control device;

[0030] The upper flow control device is used to control the fluid flow of the first branch completion string in the first branch wellbore;

[0031] The upper downhole monitoring device is used to obtain various sensor data measured downhole;

[0032] The upper coupling device and the locking device pass through the first middle isolation device and the second middle isolation device, and are connected to the first middle coupling device of the middle completion pipe string.

[0033] In a second aspect, the present invention provides a multi-branch well completion method, comprising:

[0034] Deploy a lower completion string to the lower part of the main wellbore, and extend a second branch wellbore from the main wellbore;

[0035] Connecting the second branch wellbore to the main wellbore using a lower lateral deflection device of the lower completion string;

[0036] deploying a second branch completion string into the second branch wellbore through a lower lateral deflection device;

[0037] A middle completion string is run into the main wellbore to achieve connection between the middle completion string and the lower completion string;

[0038] Drilling a first branch wellbore from the main wellbore, and after the first branch wellbore is completed, connecting the first branch wellbore with the main wellbore using a middle lateral deflection device;

[0039] deploying a first branch completion string into the first branch wellbore through a middle lateral deflection device;

[0040] An upper completion pipe string is lowered into the main wellbore, and the upper completion pipe string is connected with the middle completion pipe string to realize signal transmission between the upper completion pipe string and the middle completion pipe string.

[0041] In some embodiments, the lower completion string is deployed by:

[0042] The lower completion string is sent into the lower part of the main wellbore, and the second lower isolation device and the third lower isolation device are deployed below the second branch wellbore and the lower part of the main wellbore, and the first lower isolation device is deployed above the second branch wellbore.

[0043] In some embodiments, the second branch completion string is deployed in the following manner:

[0044] The second tieback device of the second branch completion string is coupled to one end of the lower multi-directional connection device, and the other end of the lower multi-directional connection device is extended to the main wellbore and connected upward to the first lower isolation device located above the second branch wellbore.

[0045] In some embodiments, the middle completion string is deployed in the following manner:

[0046] Sending the middle completion pipe string into the middle of the main wellbore, and connecting the second middle coupling device with the first lower isolation device to achieve docking of the middle completion pipe string with the lower completion pipe string;

[0047] The second middle isolation device and the first middle coupling device are deployed below the first branch wellbore, and the first middle isolation device is deployed above the first branch wellbore.

[0048] In some embodiments, the first branch completion string is deployed in the following manner:

[0049] The first tieback device of the first branch completion string is coupled to one end of the middle multi-directional connection device, and the other end of the middle multi-directional connection device is extended to the main wellbore and connected upward to the first middle isolation device located above the first branch wellbore.

[0050] In some embodiments, the upper completion string is deployed as follows:

[0051] The upper completion string is lowered into the upper part of the main wellbore, and the upper coupling device and the locking device are passed through the first middle isolation device and the second middle isolation device to be connected with the first middle coupling device of the middle completion string.

[0052] In some embodiments, the method further comprises:

[0053] The central pipe is installed inside the upper isolation device to complete the central pipe well.

[0054] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0055] The multi-branch well completion system provided by the present invention connects the main wellbore and the first branch wellbore through the middle lateral deflection device, connects the main wellbore and the second branch wellbore through the lower lateral deflection device, and can deploy the first branch completion pipe string into the first branch wellbore through the middle lateral deflection device, and deploy the second branch completion pipe string into the second branch wellbore; and, through one end of the middle multi-directional connection device coupled with the first return device of the first branch completion pipe string, the other end extends to the main wellbore, and upwardly connects with the first middle isolation device located above the first branch wellbore, so as to realize the docking of the first branch completion pipe string with the upper completion pipe string, and the docking of the second branch completion pipe string with the middle completion pipe string. When the branch completion pipe string is deployed into the branch wellbore, the components in the branch completion pipe string do not need to pass through the multilateral connection device with a very small gap, thereby reducing the risk of damage to the components. The lower completion pipe string is first deployed in the lower section of the branch wellbore and the main wellbore in the well. Then, the middle completion pipe string can be lowered into the well and connected with the lower completion pipe string. Subsequently, one or more lateral wellbores may be drilled and cemented. After one or more lateral wellbores are drilled, the upper completion string is deployed downhole and connected to the middle completion string to achieve electrical or hydraulic communication with the installed portion of the string downhole.

[0056] Each completion pipe string of the present invention is connected to other completion pipe strings through a coupling device. When a completion pipe string fails, the completion pipe string can be independently pulled out for maintenance, thereby improving maintenance efficiency.

[0057] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 is a schematic structural diagram of a multi-branch well completion system provided by an embodiment of the present invention;

[0061] In the figure: 100, multi-branch well completion system; 101, main wellbore; 102, casing; 103, center pipe; 104, first oil pipe; 105, second oil pipe; 106, first branch wellbore; 107, second branch wellbore;

[0062] 110, upper completion string; 1101, upper isolation device; 1102, upper flow control device; 1103, upper downhole monitoring device; 1104, upper coupling device; 1105, locking device;

[0063] 120, middle completion string; 1201, first middle isolation device; 1202, middle multi-directional connection device; 1203, middle lateral deflection device; 1204, second middle isolation device; 1205, first middle coupling device; 1206, first middle flow control device; 1207, middle downhole monitoring device; 1208, second middle flow control device; 1209, second middle coupling device;

[0064] 130, lower completion string; 1301, first lower isolation device; 1302, lower multi-directional connection device; 1303, lower lateral deflection device; 1304, second lower isolation device; 1305, filtration device; 1306, third lower isolation device; 1307, lower sand control screen assembly;

[0065] 140, first branch completion string; 1401, first tie-back device; 1402, first branch isolation device; 1403, first branch sand control screen assembly;

[0066] 150. Second branch completion pipe string; 1501. Second tie-back device; 1502. Second branch isolation device; 1503. Second branch sand control screen assembly. DETAILED DESCRIPTION

[0067] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0068] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0069] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0070] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] In the prior art, a branch pipe string is lowered into a branch wellbore through a multilateral connection device. The inventor found in his work that some problems occurred when the production liquid flow of the lateral branch wellbore and the main wellbore was independently monitored and controlled. For example, the downhole flow control valve, downhole instrument, downhole cable and control line pass through a multilateral connection device with a very small gap. The too small gap increases the possibility of damage to these components. In addition, if the existing completion pipe string is to connect the downhole main wellbore with other branch wellbores, the pipe strings that need to be lowered are layer by layer. The size of the bottom completion pipe string is the largest, and then the size of the completion pipe string from bottom to top becomes smaller layer by layer, which results in the size of the completion pipe being limited to a very small size when the completion pipe is lowered. The smaller size of the completion pipe will be lowered into the topmost completion pipe string, but the too small size of the pipe will limit the maximum production of the oil well. At the same time, the lowering of the smaller size of the completion pipe will also cause buckling problems, thereby affecting the production life of the oil well, which cannot meet the inventor's expectations. In order to improve the completion architecture of multi-branch well intelligent completion, the inventors made the present invention after further research and development, providing a new and enhanced completion design and deployment method for multi-branch wells.

[0072] Embodiment 1

[0073] The embodiment of the present invention provides a multi-branch well completion system, referring to Figure 1As shown, it includes: an upper completion pipe string 110, a middle completion pipe string 120 and a lower completion pipe string 130 which are sequentially deployed in the main wellbore 101 from top to bottom, a first branch completion pipe string 140 which is deployed in the first branch wellbore 106 and a second branch completion pipe string 150 which is deployed in the second branch wellbore 107;

[0074] The middle completion pipe string 120 includes a first middle isolation device 1201, a middle multi-directional connection device 1202, a middle lateral deflection device 1203, a first middle coupling device 1205 and a second middle coupling device 1209;

[0075] The lower completion string 130 includes a first lower isolation device 1301, a lower multi-directional connection device 1302 and a lower lateral deflection device 1303;

[0076] The middle lateral deflection device 1203 is connected to the main wellbore 101 and the first branch wellbore 106, and is used to deploy the first branch completion string 140 into the first branch wellbore 106;

[0077] One end of the middle multi-directional connection device 1202 is coupled to the first tie-back device 1401 of the first branch completion string 140, and the other end extends to the main wellbore 101 and is upwardly connected to the first middle isolation device 1201 located above the first branch wellbore 106;

[0078] The lower lateral deflection device 1303 is connected to the main wellbore 101 and the second branch wellbore 107, and is used to deploy the second branch completion string 150 into the second branch wellbore 107;

[0079] One end of the lower multi-directional connection device 1302 is coupled to the second tie-back device 1501 of the second branch completion pipe string 150 , and the other end extends to the main wellbore 101 and is upwardly connected to the first lower isolation device 1301 located above the second branch wellbore 107 .

[0080] The above-mentioned middle lateral deflection device 1203 and the lower lateral deflection device 1303 are a deflector with a certain opening that is sleeved in the completion pipe string and can connect the main wellbore 101 and the branch wellbore. Its specific structure can refer to the description in the prior art and will not be repeated here. The above-mentioned middle multi-directional connection device 1202 and the lower multi-directional connection device 1302 are a connecting pipe string, which connects the branch completion pipe string deployed in the branch wellbore with the completion pipe string deployed in the main wellbore 101. It should be noted that, for the sake of ease of explanation, the present invention only shows one middle completion pipe string 120 and two branch wellbores. The number of the above-mentioned middle completion pipe string 120 is not limited to one, and the corresponding number of branch wellbores is not limited to two. There may be multiple middle completion pipe strings 120. When there are multiple middle completion pipe strings 120, the tie-back device of the branch completion pipe string in the branch wellbore is connected to the first middle isolation device 1201 of the middle completion pipe string 120 located above the branch wellbore through a multi-directional connection device.

[0081] The multi-branch well completion system provided by the present invention relates to the field of oil and natural gas cementing technology. The main wellbore 101 and the first branch wellbore 106 are connected through the middle lateral deflection device 1203, and the main wellbore 101 and the second branch wellbore 107 are connected through the lower lateral deflection device 1303. The first branch completion pipe string 140 can be deployed into the first branch wellbore 106 through the middle lateral deflection device 1203, and the second branch completion pipe string 150 can be deployed into the second branch wellbore 107; and the middle multi-directional connection device 1202 can be used to connect the main wellbore 101 and the second branch wellbore 107. The first end of the first branch completion pipe string 140 is coupled with the first tie-back device 1401, and the other end extends to the main wellbore 101, and is connected upward to the first middle isolation device 1201 located above the first branch wellbore 106, so as to achieve the docking of the first branch completion pipe string 140 with the upper completion pipe string 110, and the docking of the second branch completion pipe string 150 with the middle completion pipe string 120. When the branch completion pipe string is deployed into the branch wellbore, the components in the branch completion pipe string do not need to pass through the multilateral connection device with a very small gap, thereby reducing the risk of damage to the components. The lower completion pipe string 130 is first deployed in the lower section of the second branch wellbore 107 and the main wellbore 101 underground. Then, the middle completion pipe string 120 can be lowered into the well and connected with the lower completion pipe string 130. Subsequently, one or more branch wellbores can be drilled and cemented. After drilling one or more branch wellbores, the upper completion string 110 is deployed underground and connected to the middle completion string 120 to achieve electrical or hydraulic communication with the installed partial strings underground.

[0082] In a specific embodiment, the upper completion string 110 includes an upper coupling device 1104;

[0083] The middle completion pipe string 120 includes a first middle coupling device 1205 and a second middle coupling device 1209;

[0084] The lower completion string 130 includes a first lower isolation device 1301;

[0085] The upper coupling device 1104 is connected to the first middle coupling device 1205; the upper coupling device 1104 is a male connector, and the first middle coupling device 1205 is a female connector. When the first middle coupling device 1205 of the middle completion string 120 is connected to the upper coupling device 1104 of the upper completion string 110, control / data signals can be transmitted along the entire multi-branch completion system 100.

[0086] The second middle coupling device 1209 is connected to the first lower isolation device 1301 .

[0087] Adjacent completion pipe strings are connected by the above-mentioned coupling devices, so as to send control signals or data signals to various sensors, flow control devices or various other intelligent completion equipment in and / or in the well. The above-mentioned control signals and data signals can be electrical signals, hydraulic signals, hydraulic signals, optical signals and / or other signals used to control downhole components and collect data from downhole sensors. The upper completion pipe string 110, the middle completion pipe string 120 and the lower completion pipe string 130 in the present invention all include coupling devices with hydraulic and electric coupling capabilities. The upper coupling device 1104 of the upper completion pipe string 110 is connected to the first middle coupling device 1205 of the middle completion pipe string 120, and the second middle coupling device 1209 of the middle completion pipe string 120 is connected to the first lower isolation device 1301 of the lower completion pipe string 130. By setting the coupling device, the docking of each completion pipe string can be achieved. The various completion pipe strings of the present invention are connected by coupling, and the sizes of the lower, middle and upper completion pipe strings can be consistent. Compared with the method of reducing the size of the completion pipe strings in the prior art layer by layer, the present invention can use larger completion pipe strings, thereby ensuring that the size of the production pipe column inserted is the maximum, so as to help maximize production and improve oil well production, and solve the problem of affecting the production life of the oil well due to the easy buckling of the oil pipe due to the small size.

[0088] In a specific embodiment, the lower completion string 130 further includes: a second lower isolation device 1304, a filtration device 1305, a third lower isolation device 1306 and a lower sand control screen assembly 1307 connected in sequence from top to bottom by the oil pipe;

[0089] The first lower isolation device 1301 is located above the second branch wellbore 107, and the second lower isolation device 1304 is located below the second branch wellbore 107. The first lower isolation device 1301 and the second lower isolation device are used to isolate the oil casing annulus therebetween.

[0090] The first lower isolation device 1301, the second lower isolation device 1304 and the third lower isolation device 1306 are packers that can be used for sealing and anchoring. The structure of the filtration device 1305 can refer to the description in the prior art, and will not be repeated here.

[0091] In a specific embodiment, the second branch completion pipe string 150 includes a second branch isolation device 1502 and a second branch sand control screen assembly 1503 connected by an oil pipe; the second branch isolation device 1502 is used to isolate the casing annulus in the second branch wellbore 107, and the second branch sand control screen assembly 1503 is a measure tool to prevent sand blockage during oil production.

[0092] The second tie-back device 1501 is coupled to one end of the lower multi-directional connection device 1302;

[0093] The other end of the lower multi-directional connection device 1302 extends to the main wellbore 101 and is connected to the first lower isolation device 1301 .

[0094] The first completion string deployed in the second branch wellbore 107 may include a second branch completion string 150 having a plurality of completion components, such as a second branch sand screen assembly 1503 or other suitable components placed along the second oil pipe 105 and separated by a second branch isolation device 1502. The second branch wellbore 107 may be in fluid communication with the main wellbore 101 through a lower multi-directional connection device 1302 coupled to a second tieback device 1501 located in the second branch wellbore 107. The lower multi-directional connection device 1302 extends to the main wellbore 101 and is connected upward to a corresponding first lower isolation device 1301 located above the second branch wellbore 107. The second branch isolation device 1502 is a packer, and of course, a variety of other types of sealing devices may also be used to achieve the required sealing and anchoring functions.

[0095] In a specific embodiment, the middle completion string 120 includes a second middle isolation device 1204, a first middle flow control device 1206, a middle downhole monitoring device 1207 and a second middle flow control device 1208 connected by an oil pipe, and the above components are connected by the first oil pipe 104;

[0096] The first central isolation device 1201 is installed on the central lateral deflection device 1203, and the central lateral deflection device 1203 is connected to the second central isolation device 1204; the first central isolation device 1201 can be a sealer or other sealing device with the required sealing, anchoring and / or orientation functions, and the corresponding first central isolation device 1201 is installed on or connected to the central lateral deflection device 1203.

[0097] The first middle isolation device 1201 is located above the first branch wellbore 106, and the second middle isolation device 1204 is located below the first branch wellbore 106; the first middle isolation device 1201 and the second middle isolation device 1204 are respectively located above and below the first branch wellbore 106, and after the first middle isolation device 1201 and the second middle isolation device 1204 are sealed, the oil casing annulus between the two can be isolated.

[0098] The first middle flow control device 1206 is used to control the flow of fluid flowing from the main wellbore 101 through the middle completion string 120;

[0099] The second middle flow control device 1208 is used to control the flow of fluid flowing from the second branch wellbore 107 through the middle completion string 120;

[0100] The middle downhole monitoring device 1207 is used to obtain various sensor data of downhole measurements.

[0101] The multi-branch well completion system 100 also includes a middle completion string 120, which is lowered into the main wellbore 101 and delivered to the junction of the lower completion string 130. The middle completion string 120 may include various other components, including a permanent middle downhole monitoring device 1207 and a first middle flow control device 1206 and a second middle flow control device 1208 for the main wellbore 101 and the second branch wellbore 107. For example, the middle downhole monitoring device 1207 may include various sensors for obtaining downhole measurements, such as pressure measurement, temperature measurement, flow measurement, water content measurement, gas content measurement and / or other downhole data. The pipelines of the first middle flow control device 1206 and the second middle flow control device 1208 are respectively connected to different pipe strings, wherein the channel of the first middle flow control device 1206 is connected to the middle completion pipe string 120, and is used to control the fluid flow flowing from the main wellbore 101 through the middle completion pipe string 120; the pipeline of the second middle flow control device 1208 is connected to the second branch completion pipe string 150, and is used to control the fluid flow flowing from the second branch wellbore 107 through the middle completion pipe string 120.

[0102] In a specific embodiment, the first branch completion pipe string 140 further includes a first branch isolation device 1402 and a first branch sand control screen assembly 1403 connected by oil pipes. The first branch completion pipe string 140 includes but is not limited to the above completion assembly. The first branch isolation device 1402 is used to isolate the oil casing annulus in the first branch wellbore 106, and the first branch sand control screen assembly 1403 is a measure tool to prevent sand plugging during oil production.

[0103] In a specific embodiment, the multi-branch well completion system 100 may further include an upper completion pipe string 110, which may be transported downhole and connected to the middle completion pipe string 120. The upper completion pipe string 110 includes an upper isolation device 1101, an upper flow control device 1102, an upper downhole monitoring device 1103, and a locking device 1105 connected by oil pipes; the upper coupling device 1104 is a joint-type coupling device, which can quickly and easily replace the completion oil pipe above the upper isolation device 1101. There is no need to recover and replace the downhole monitoring device and the flow control device, and the use of the joint-type coupling device reduces the cost, time, and complexity of well repair.

[0104] The first middle coupling device 1205 (female connector) of the middle completion string 120 is connected to the upper coupling device 1104 (male connector) of the upper completion string 110, and the upper coupling device 1104 (male connector) is sent downhole through the central pipe 103, and the central pipe 103 can pass the locking device 1105 and the upper coupling device 1104 through the first middle isolation device 1201 and the second middle isolation device 1204. The central pipe 103 can extend upward and connect with other upper completion components, such as the upper downhole monitoring device 1103 and the upper flow control device 1102. The upper downhole monitoring device 1103 may include various sensors for obtaining downhole measurements, such as pressure measurement, temperature measurement, flow measurement, water content measurement, cavitation measurement and / or other downhole data. The upper flow control device 1102 can be used to control the fluid flow of the first branch completion string 140 in the first branch wellbore 106. The upper completion string 110 may further include an upper isolation device 1101 located above the upper flow control device 1102 .

[0105] The upper isolation device 1101 is located above the upper flow control device 1102;

[0106] The upper flow control device 1102 is used to control the fluid flow of the first branch completion string 140 in the first branch wellbore 106;

[0107] The upper downhole monitoring device 1103 is used to obtain various sensor data measured downhole;

[0108] The upper coupling device 1104 and the locking device 1105 pass through the first middle isolation device 1201 and the second middle isolation device 1204 , and are connected to the first middle coupling device 1205 of the middle completion pipe string 120 .

[0109] Embodiment 2

[0110] An embodiment of the present invention provides a multi-branch well completion method, comprising:

[0111] S101, deploy the lower completion string 130 to the lower part of the main wellbore 101, and extend the second branch wellbore 107 from the main wellbore 101; perform preliminary drilling and run casing 102 into the main wellbore 101 to install the corresponding components of the lower completion string 130. Then, the second branch wellbore 107 may be drilled and run casing 102 into to install the corresponding components of the second branch completion string 150.

[0112] S102, using the lower lateral deflection device 1303 of the lower completion string 130 to connect the second branch wellbore 107 with the main wellbore 101;

[0113] S103, deploying the second branch completion string 150 into the second branch wellbore 107 through the lower lateral deflection device 1303;

[0114] S104. Lower the middle completion string 120 into the main wellbore 101 to achieve docking between the middle completion string 120 and the lower completion string 130. Depending on the operating parameters, the middle completion string 120 can be lowered alone underground or used in combination with the lower lateral deflection device 1303 to allow the second branch completion string 150 to smoothly enter the second branch wellbore 107.

[0115] S105, drilling the first branch wellbore 106 from the main wellbore 101. After the first branch wellbore 106 is completed, the middle lateral deflection device 1203 is used to connect the first branch wellbore 106 with the main wellbore 101. The middle lateral deflection device 1203 facilitates the subsequent drilling and completion of the first branch wellbore 106, and the installation of the upper completion pipe string 110 into the main wellbore 101, and is connected to the middle completion pipe string 120 through the upper coupling device 1104 (male connector). After the middle completion pipe string 120 is lowered into the well, the first branch wellbore 106 can be drilled and the casing 102 can be lowered. According to the parameters of the given operation, the middle lateral deflection device 1203 is connected to the middle completion pipe string 120 at an appropriate time to facilitate the deployment of the first branch completion pipe string 140 into the first branch wellbore 106, and form a connection between the main wellbore 101 and the first branch wellbore 106.

[0116] S106, deploying the first branch completion string 140 into the first branch wellbore 106 through the middle lateral deflection device 1203;

[0117] S107 , lowering the upper completion pipe string 110 into the main wellbore 101 , and connecting the upper completion pipe string 110 with the middle completion pipe string 120 to achieve signal transmission between the upper completion pipe string 110 and the middle completion pipe string 120 .

[0118] In a specific embodiment, the lower completion string 130 is deployed in the following manner:

[0119] The lower completion string 130 is sent into the lower part of the main wellbore 101, and the second lower isolation device 1304 and the third lower isolation device 1306 are deployed below the second branch wellbore 107 and the lower part of the main wellbore 101, and the first lower isolation device 1301 is deployed above the second branch wellbore 107. The lower completion string 130 can form a connection between the main wellbore 101 and the second branch wellbore 107, the first lower isolation device 1301 of the lower completion string 130 is deployed above the second branch wellbore 107, and the second lower isolation device 1304 of the lower completion string 130 is deployed below the second branch wellbore 107, so as to isolate the oil casing annulus between the first lower isolation device 1301 and the second lower isolation device 1304.

[0120] In a specific embodiment, the second branch completion string 150 is deployed in the following manner:

[0121] The second tieback device 1501 of the second branch completion string 150 is coupled to one end of the lower multi-directional connection device 1302, and the other end of the lower multi-directional connection device 1302 is extended to the main wellbore 101 and upwardly connected to the first lower isolation device 1301 located above the second branch wellbore 107. Deploying the second branch completion string 150 includes deploying a plurality of second branch sand control screen assemblies 1503 into the second branch wellbore 107. The second branch sand control screen assemblies 1503 are located in the second branch wellbore 107 and are connected to the main wellbore 101 through the lower multi-directional connection device 1302 and the second tieback device 1501.

[0122] In a specific embodiment, the middle completion string 120 is deployed in the following manner:

[0123] The lowering of the middle completion string 120 includes forming a connection coupling between the upper completion string 110 and the middle completion string 120 using a joint matching coupler. The lowering of the middle completion string 120 includes a first middle coupling device 1205 and a second middle coupling device 1209 that provide joint matching coupling capabilities at multiple positions along the main wellbore 101. Specifically, the middle completion string 120 is sent into the middle of the main wellbore 101, and the second middle coupling device 1209 is connected to the first lower isolation device 1301 to achieve the docking of the middle completion string 120 with the lower completion string 130; once the lower completion string 130 is installed, the middle completion string 120 can be lowered into the well and connected to the lower completion string 130 through the first lower isolation device 1301. When installing the upper completion string 110, the first middle coupling device 1205 (female connector) is used to receive the upper coupling device 1104 (male connector) of the upper completion string 110. A middle completion string 120 is lowered into the well to provide permanent downhole monitoring and flow control for the main wellbore 101 and the second branch wellbore 107 extending from the main wellbore 101; then, after drilling the first branch wellbore 106, the upper completion string 110 is sent into the well and communicates with the middle completion string 120 through a connector with signal communication capability, namely the upper coupling device 1104.

[0124] The second middle isolation device 1204 and the first middle coupling device 1205 are deployed below the first branch wellbore 106 , and the first middle isolation device 1201 is deployed above the first branch wellbore 106 .

[0125] In a specific embodiment, the first branch completion string 140 is deployed in the following manner:

[0126] The first tieback device 1401 of the first branch completion pipe string 140 is coupled to one end of the middle multi-directional connection device 1202, and the other end of the middle multi-directional connection device 1202 is extended to the main wellbore 101, and upwardly connected to the first middle isolation device 1201 located above the first branch wellbore 106, so that the first branch completion pipe string 140 is connected to the middle completion pipe string 120. Deploying the first branch completion pipe string 140 to the first branch wellbore 106 includes the first branch isolation device 1402 and the first branch sand control screen assembly 1403 in the first branch wellbore 106. The first branch sand control screen assembly 1403 is located in the first branch wellbore 106, and is connected to the main wellbore 101 through the middle multi-directional connection device 1202 and the first tieback device 1401.

[0127] In a specific embodiment, the upper completion string 110 is deployed in the following manner:

[0128] After the first branch wellbore 106 is connected to the main wellbore 101 using the middle lateral deflection device 1203, the upper completion string 110 is installed. The upper completion string 110 is lowered into the upper part of the main wellbore 101, and the upper coupling device 1104 and the locking device 1105 are passed through the first middle isolation device 1201 and the second middle isolation device 1204 to connect with the first middle coupling device 1205 of the middle completion string 120. Transporting the upper completion string 110 includes installing the upper isolation device 1101, and installing the upper downhole monitoring device 1103 and the upper flow control device 1102. The upper completion string 110 can be connected to the first middle coupling device 1205 of the middle completion string 120 through the locking device 1105 and the upper coupling device 1104 to achieve communication of required signals, such as electrical, hydraulic, electro-hydraulic and / or optical signals. The installation of the upper completion string 110 includes installing an upper downhole monitoring device 1103 and an upper flow control device 1102 .

[0129] In a specific embodiment, the method further comprises:

[0130] The central pipe 103 is installed inside the upper isolation device 1101 to achieve central pipe completion.

[0131] In the embodiment of the present invention, the multi-branch well completion method corresponds to the multi-branch well completion system described in the above embodiment 1. Its specific implementation process can refer to the process of completing the well using the multi-branch well completion system in the above embodiment 1. The repeated parts will not be repeated here.

[0132] In this document, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. The orientation or position relationship indicated by the terms "upper", "lower", etc. is based on the orientation or position relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0133] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. The present invention is not limited to any single aspect, any single embodiment, or any combination and / or permutation of these aspects and / or embodiments. Each aspect and / or embodiment of the present invention can be used alone, or in combination with one or more other aspects and / or other embodiments.

[0134] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A multi-branch well completion system, characterized in that: include: An upper completion pipe string (110), a middle completion pipe string (120) and a lower completion pipe string (130) are sequentially deployed in the main wellbore (101) from top to bottom, as well as a first branch completion pipe string (140) deployed in the first branch wellbore (106) and a second branch completion pipe string (150) deployed in the second branch wellbore (107); The middle completion pipe string (120) comprises a first middle isolation device (1201), a middle multi-directional connection device (1202), a middle lateral deflection device (1203), a first middle coupling device (1205) and a second middle coupling device (1209); The lower completion string (130) comprises a first lower isolation device (1301), a lower multi-directional connection device (1302) and a lower lateral deflection device (1303); The middle lateral deflection device (1203) is connected to the main wellbore (101) and the first branch wellbore (106), and is used to deploy the first branch completion string (140) into the first branch wellbore (106); One end of the middle multi-directional connection device (1202) is coupled to the first tie-back device (1401) of the first branch completion string (140), and the other end extends to the main wellbore (101) and is upwardly connected to the first middle isolation device (1201) located above the first branch wellbore (106); The lower lateral deflection device (1303) is connected to the main wellbore (101) and the second branch wellbore (107), and is used to deploy the second branch completion string (150) into the second branch wellbore (107); One end of the lower multi-directional connection device (1302) is coupled to the second tie-back device (1501) of the second branch completion pipe string (150), and the other end extends to the main wellbore (101) and is upwardly connected to the first lower isolation device (1301) located above the second branch wellbore (107).

2. The multi-branch well completion system according to claim 1, characterized in that: The upper completion string (110) comprises an upper coupling device (1104); The middle completion pipe string (120) comprises a first middle coupling device (1205) and a second middle coupling device (1209); The lower completion string (130) comprises a first lower isolation device (1301); The upper coupling device (1104) is connected to the first middle coupling device (1205); The second middle coupling device (1209) is connected to the first lower isolation device (1301).

3. The multi-branch well completion system according to claim 1, characterized in that: The lower completion pipe string (130) further comprises: a second lower isolation device (1304), a filtration device (1305), a third lower isolation device (1306) and a lower sand control screen assembly (1307) which are sequentially connected from top to bottom by the oil pipe; The first lower isolation device (1301) is located above the second branch wellbore (107), and the second lower isolation device (1304) is located below the second branch wellbore (107).

4. The multi-branch well completion system according to claim 3, characterized in that: The second branch completion pipe string (150) comprises a second branch isolation device (1502) and a second branch sand control screen assembly (1503) connected by an oil pipe; The second tie-back device (1501) is coupled to one end of the lower multi-directional connection device (1302); The other end of the lower multi-directional connection device (1302) extends to the main wellbore (101) and is connected to the first lower isolation device (1301).

5. The multi-branch well completion system according to claim 1, characterized in that: The middle completion pipe string (120) comprises a second middle isolation device (1204), a first middle flow control device (1206), a middle downhole monitoring device (1207) and a second middle flow control device (1208) connected by oil pipes; The first middle isolation device (1201) is installed on the middle lateral deflection device (1203), and the middle lateral deflection device (1203) is connected to the second middle isolation device (1204); The first middle isolation device (1201) is located above the first branch wellbore (106), and the second middle isolation device (1204) is located below the first branch wellbore (106); The first middle flow control device (1206) is used to control the flow of fluid flowing from the main wellbore (101) through the middle completion string (120); The second middle flow control device (1208) is used to control the flow of fluid flowing from the second branch wellbore (107) through the middle completion string (120); The middle downhole monitoring device (1207) is used to obtain various sensor data of downhole measurements.

6. The multi-branch well completion system according to claim 5, characterized in that: The first branch completion pipe string (140) further comprises a first branch isolation device (1402) and a first branch sand control screen assembly (1403) connected by oil pipes.

7. The multi-branch well completion system according to claim 5, characterized in that: The upper completion pipe string (110) comprises an upper isolation device (1101), an upper flow control device (1102), an upper downhole monitoring device (1103) and a locking device (1105) connected by oil pipes; The upper isolation device (1101) is located above the upper flow control device (1102); The upper flow control device (1102) is used to control the fluid flow of the first branch completion string (140) in the first branch wellbore (106); The upper downhole monitoring device (1103) is used to obtain various sensor data measured downhole; The upper coupling device (1104) and the locking device (1105) pass through the first middle isolation device (1201) and the second middle isolation device (1204), and are connected to the first middle coupling device (1205) of the middle completion pipe string (120).

8. A multi-branch well completion method, characterized in that: include: Deploy a lower completion string (130) to the lower part of the main wellbore (101), and extend a second branch wellbore (107) from the main wellbore (101); Using the lower lateral deflection device (1303) of the lower completion string (130) to connect the second branch wellbore (107) with the main wellbore (101); Deploying a second branch completion string (150) into a second branch wellbore (107) via a lower lateral deflection device (1303); Lowering a middle completion pipe string (120) into the main wellbore (101) to achieve docking between the middle completion pipe string (120) and the lower completion pipe string (130); Drilling a first branch wellbore (106) extending from the main wellbore (101), and after the first branch wellbore (106) is completed, connecting the first branch wellbore (106) with the main wellbore (101) using a middle lateral deflection device (1203); Deploying a first branch completion string (140) into a first branch wellbore (106) via a middle lateral deflection device (1203); An upper completion pipe string (110) is lowered into the main wellbore (101), and the upper completion pipe string (110) is connected to a middle completion pipe string (120) to achieve signal transmission between the upper completion pipe string (110) and the middle completion pipe string (120).

9. The multi-branch well completion method according to claim 8, characterized in that: The lower completion string (130) is deployed by: The lower completion string (130) is sent into the lower part of the main wellbore (101), and the second lower isolation device (1304) and the third lower isolation device (1306) are deployed below the second branch wellbore (107) and the lower part of the main wellbore (101), and the first lower isolation device (1301) is deployed above the second branch wellbore (107).

10. The multi-branch well completion method according to claim 8, characterized in that: The second branch completion string (150) is deployed in the following manner: The second tie-back device (1501) of the second branch completion pipe string (150) is coupled to one end of the lower multi-directional connection device (1302), and the other end of the lower multi-directional connection device (1302) is extended to the main wellbore (101) and connected upward to the first lower isolation device (1301) located above the second branch wellbore (107).

11. The multi-branch well completion method according to claim 8, characterized in that: The middle completion string (120) is deployed in the following manner: Sending the middle completion pipe string (120) into the middle of the main wellbore (101), and connecting the second middle coupling device (1209) with the first lower isolation device (1301), so as to achieve docking of the middle completion pipe string (120) with the lower completion pipe string (130); The second middle isolation device (1204) and the first middle coupling device (1205) are deployed below the first branch wellbore (106), and the first middle isolation device (1201) is deployed above the first branch wellbore (106).

12. The multi-branch well completion method according to claim 8, characterized in that: The first branch completion string (140) is deployed in the following manner: The first tie-back device (1401) of the first branch completion pipe string (140) is coupled to one end of the middle multi-directional connection device (1202), and the other end of the middle multi-directional connection device (1202) is extended to the main wellbore (101) and connected upward to the first middle isolation device (1201) located above the first branch wellbore (106).

13. The multi-branch well completion method according to claim 11, characterized in that: The upper completion string (110) is deployed in the following manner: The upper completion string (110) is lowered into the upper part of the main wellbore (101), and the upper coupling device (1104) and the locking device (1105) are passed through the first middle isolation device (1201) and the second middle isolation device (1204), and connected to the first middle coupling device (1205) of the middle completion string (120).

14. The multi-branch well completion method according to claim 8, characterized in that: The method further comprises: The central pipe (103) is installed inside the upper isolation device (1101) to achieve central pipe completion.

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